This invention relates to a method for producing polymer bonded nitramine explosives and propellants by radiation polymerization.
Polymer bonded cast explosives and propellants usually contain one or more solid explosive or propellant components bonded together in a matrix of a solid polymeric binder. They can be produced by polymerizing a monomer, such as methyl methacrylate, mixed with a particulate explosive or propellant component, by means of a chemical polymerization catalyst, such as an organic peroxide, or by means of high energy radiation, such as x-rays or gamma rays.
Radiation polymerization provides a number of important advantages of the manufacture of polymer bonded explosives and propellants. Thus, it permits the use of lower polymerization temperatures, which increases the safety of working with mixtures containing sensitive explosive and propellant components, and leaves no catalyst residue in the product. Also, the solid explosive/propellant components can be slurried with the liquid monomer and cast in situ in rocket and projectile casings by radiation. Further, granules of the explosive/propellant components can be coated with the liquid monomer, and the coated granules pressed into rocket casings, large caliber projectile casings, shaped charge rounds, etc. and cured to a hard, solid charge by radiation. Since the compositions are devoid of chemical polymerization catalysts, they possess essentially unlimited "pot life", which is a significant advantage in manufacturing operations.
It is known to prepare radiation cured, polymer bonded explosive and propellant compositions containing inorganic oxidizers, such as ammonium nitrate, ammonium perchlorate, and potassium perchlorate (e.g. U.S. Pat. No. 3,145,528), and organic oxidizers such as nitro compounds, e.g. lead styphnate, trinitrotoluene and pentaerythritol tetranitrate (U.S. Pat. No. 4,056,416). Attempts to produce polymer bonded explosive compositions by radiation polymerization in similar manner using nitramine explosive components have not been successful. It is believed that the nitro groups present as nitramines inhibit the polymerization reaction by intercepting the active transients (free radicals).
Accordingly, it is an object of the present invention to provide a process for producing polymer bonded explosives/propellants containing nitramine components by radiation polymerization.